If you are VERy performance oriented you ideally want to find a very lightweight 17" wheel (14-19 lbs each) in a unstaggered setup. If you go with a really heavy wheel you'll defintely notice a decrease in acceleration due to the extra unsprung weight. You should look in the offsets of +37 to +43. The higher the offset the more the wheel will be in. So a wheel with a +35 offset would stick out further than a wheel with +35. So if you buy a wheel with 43 offset and find they rub a little bit on the inside you can add 3 to 5 mm spacers and you could have a wheel with 40 to 38 mm offset. They also sell spacers in larger sizes. The bolt pattern you need is 5x120mm
Going with wider tires in the rear has the obvious pro for traction but has the major cons of increasing understeer, and not being able to rotate tires front and back.
As Mark recommended, 18's with 235/40 tires. Roll fenders for good clearance and less chance of rubbing. There are a boat load of wheel options out there. Keep an eye on the wheel/tire classifieds section on our site as well as check out www.tirerack.com
I currently have 18" wheels with a 35 mm offset, with 235/40/18 tires I have yet to put on. I have my rear fenders rolled. Im hoping they will fit but im pushing it close.
For your frotn struts you should get some Koni Single Adjustable struts. They have the ability to adjust dampening (how soft or stiff your ride is). Koni SA's are an insert so you would need ot keep your stock front struts and insert the Koni's into them. Another greta option is Bilstein Sports. If you arent looking for adjustable or super sporty handling you could defintely go with somethign factory feeling liek Bilstein Heavy Duty.